August 21, 2014

An international team of biologists has discovered living microbes and an active ecosystem located one-half mile beneath the surface of the West Antarctic Ice Sheet, according to new research published online Wednesday in the journal Nature.

The study, which was funded by the National Science Foundation (NSF) and led by Montana State University professor John Priscu, collected samples from subglacial Lake Whillans, which is located beneath more than 2600 feet of ice and has not been exposed to wind or sunlight for several million years. They discovered that this lake “supports a metabolically active and… diverse ecosystem that functions in the dark at subzero temperatures.”

The life they discovered there is microorganisms that convert ammonium and methane into the energy required for growth, the researchers explained. According to Scientific American reporter Douglas Fox, Priscu and his colleagues discovered 130,000 cells in each milliliter of lake water – microbial life density similar to that found in the world’s deep oceans.

The researchers found nearly 4,000 species of bacteria and archaea living in the subglacial lake, making the community far more complex than the study authors expected to see in a region largely shut off from the rest of the world, Fox said. The discovery is part of the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project, which involved more than two dozen experts from 15 universities in five different countries.

Thus far, only single-celled organisms have been detected in the samples, but the DNA tests used were not designed to detect more evolved creatures – meaning that Lake Whillans could be home to more complex creatures found elsewhere in Antarctica, such as protozoa, rotifers, worms or eight-legged tardigrades, though the low rate of carbon fixation by the microbes might not provide enough food for multicellular life forms, Fox added.

“We were able to prove unequivocally to the world that Antarctica is not a dead continent,” Priscu said in a statement, noting that their research paper (which was based on a discovery made in January 2013) provides the first direct evidence that life exists in the subglacial environment that exists beneath the Antarctic ice sheet.

“It’s the first definitive evidence that there’s not only life, but active ecosystems underneath the Antarctic ice sheet, something that we have been guessing about for decades,” added lead author Brent Christner of the Louisiana State University Department of Biological Sciences. “With this paper, we pound the table and say, “Yes, we were right.’”

Project WISSARD, which received $20 million in funding from the NSF, used newly-constructed hot-water drill technology that allowed the researchers to directly obtain water and sediment samples without contaminating either the specimens or the lake itself. NASA’s Cryospheric Sciences Program, the National Oceanic and Atmospheric Administration (NOAA), and the private Gordon and Betty Moore Foundation also supported the research.

“Because Antarctica is basically a microbial continent, exploring below its thick ice sheet can help us understand how life has evolved to survive in cold darkness,” said Jill Mikucki of the University of Tennessee. “I hope our findings motivate new research on the role of these extreme microorganisms in the function of our planet and other icy worlds in our solar system.”

According to Michael D. Lemonick of National Geographic, University of Bristol geochemist Martyn Tranter (who was not involved in the study) called the research “a landmark for the polar sciences”, and Lemonick added that it was “also a landmark in the science of astrobiology, the search for life on other worlds” because it “suggests that extraterrestrial life might also exist in places once thought uninhabitable.”

Image 2 (below): The microorganisms that came out of Subglacial Lake Whillans were “incredibly diverse,” and the microbial cells came in a variety of shapes. The yellow arrow points to a rod-shaped cell as seen through a scanning electron microscope. Credit: WISSARD